Raised Bed Soil Calculator
How much soil do you need to fill those raised beds?
How this is calculated
- Per bed = length × width × (depth ÷ 12)
- Total = per bed × number of beds
- Bags = ⌈total ÷ bag size⌉
- Bulk yards = total ÷ 27
Common questions
How much soil do I need for a 4×8 raised bed?
A 4 × 8 bed at 10 inches deep takes about 27 cu ft — one cubic yard, or 14 of the standard 2 cu ft bags. For 3 such beds, that is 80 cu ft: 2.96 bulk yards or 40 bags.
What is the best soil mix for raised beds?
The classic "Mel's mix" is 1/3 compost, 1/3 peat moss (or coco coir), 1/3 vermiculite — light and productive but pricey for deep beds. A cheaper and excellent blend: 50-60% topsoil, 30-40% compost, 10% aeration (perlite or coarse sand). Do not fill deep beds with 100% compost; it settles and compacts.
How deep should a raised bed be?
Greens and herbs: 6 in. Most vegetables: 10-12 in. Carrots, parsnips, and potatoes: 12-18 in. Beds deeper than 12 in drain better and warm up earlier in spring. You can also "double-dig" or mound native soil beneath the bed to give roots more room without filling the whole depth with purchased soil.
Can I fill the bottom of a deep bed with cheaper material?
Yes — the hugelkultur trick. Fill the bottom third with logs, branches, and leaves, then top with 8-12 in of real soil. The wood slowly breaks down, holds moisture, and saves real money on a deep bed. Avoid pressure-treated wood or walnut for the filler layer.
Bags or bulk delivery for raised beds?
Bulk soil at $20-60/yd³ beats bagged ($3-8 per 2 cu ft bag = $40-108/yd³) once you need more than about 1.5 yards. For 3+ standard beds, get bulk "garden blend" delivered; save bags for top-ups and containers.